Gear motor or pump

ABSTRACT

A multi-stage gear motor or pump utilizing a single central gear common to all stages and individual gears each cooperating with the central gear to provide the several stages. The individual gears are arranged equi-distantly from each other around and in engagement with the central gear. Portions of the housing extend between the individual gears to points close to the central gear to provide operating chambers adjacent each of the gear mesh points. Valving is arranged, preferably within the housing, to connect the operating chambers as desired, serially, parallel, by-passed or partially one and partially another. Where rotary valves are used, simple means can be provided for operating the valves simultaneously or successively from a single control.

United States Patent 1 Bschorer [54] GEAR MOTOR OR PUMP [75] Inventor:Konrad Bschorer, Wolfratshausen,

Germany [73] Assignee: Friedrich Deckel Aktiengesellschaft, Munich,Germany [22] Filed: Apr. 19, 1971 [21] Appl. No.: 135,075

[30] Foreign Application Priority Data Apr. 27, 1970 Austria ..3834

[52] US. Cl. ..418/10, 418/196, 251/249 [51] Int. Cl ..F01c l/08, F03c3/00, F04C 1/04 [58] Field of Search ..418/10, 165, 196; 74/436; 251/249[56] 1 References Cited UNITED STATES PATENTS 798,848 9/1905 Warren..418/10 1,983,216 12/1934 Carter et a1. ..418/196 226,023 3/1880Booklet ..74/436 897,595 9/1908 Crouch et al.... ..418/196 3,207,1119/1965 Giliberty ..74/436 3,523,460 8/1970 Beauvais ..251/249 748,19612/1903 Le Rond ..418/10 [111 3,724,975 51 Apr. 3, 1973 FOREIGN PATENTSOR APPLICATIONS 465,363 5/1937 Great Britain ..418/165 990,073, 5/1951France ..418/196 985,331 3/1965 Great Britain ..418/196 PrimaryExaminer-William L. Freeh Assistant Examiner-John J. VrablikA'ttomeyWoodhams, Blanchard & Flynn [57] ABSTRACT A multi-stage gearmotor or pump utilizing a single central gear common to all stages andindividual gears each cooperating with the central gear to provide theseveral stages. The individual gears are arranged equidistantly fromeach other around and in engagement with the central gear. Portions ofthe housing extend between the individual gears to points close to thecentral gear to provide operating chambers adjacent each of the gearmesh points. Valving is arranged, preferably within the housing, toconnect the operating chambers as desired, serially, parallel, by-passedor partially one and partially another. Where rotary valves are used,simple means can be provided for operating the valves simultaneously orsuccessively from a single control.

6 Claims, 23 Drawing Figures PATENIEDAPRS I975 3,724,975

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INVER'TGR PAIENIEWR 3 m5 SHEET lOUF 1O GEAR MOTOR R PUMP or driving gearis connected to the main or output shaft.

German Auslegeschrift No. 1 185 926 discloses a gear motor with morethan two gears of which one gear is connected to the output shaft. Thegears are arranged in an even number on a common circle in such a mannerthat each gear engages the two adjacent gears and all gears are therebyin direct or indirect engagement. Ports located in the housing open atthe meshing points. The ports are provided interchangeably for thefeeding or discharging of a pressure medium, said medium being admittedfrom some other point either under a high pressure or a low pressure.Thus there is provided an arrangement of several common gear motorsconnected to one another and each having two gears.

This gear motor is obviously provided to achieve a relatively greatoutput but to require only a small space. However, it has a number ofdisadvantages. First of all, the asymmetrical load is undesireable.Commencing with the gear which is the farthest from the driven gear, theindividual gears and their bearings must absorb increasing forces as oneapproaches the driven gear. The ports open in the directionof themeshing points so that a hydrodynamic operation is not possible and onlylow rotational speeds may be used. During the manufacture there existsthe difficulty of adjusting the many meshing points with respect to eachother. The arrangement uses a number of teeth which is equal in allgears so that especially at low rotational speed there existsdeficiencies with respect to the synchronism of the gear motor. Like allknown gear motors and pumps, this gear motor cannot be shifted. Knowngear motors are designed for relatively low rotational speed and thusfor a hydrostatic'or a mainly hydrostatic operation and are thereforenot suitable for high rotational speeds.

Axial piston motors or pumps and rotary rams or pumps are known onshiftable or controllable pressuremedium-operated motors or on pumpsused for conveying of fluids.

Adjustable axial piston motors, however, are expensive to manufacture,requiring joints, calottes, swash plates, an exact fitting of thepistons and a control of the inlets and outlets. Compared to the gearmotors, the oscillating forces are also disadvantageous.

Rotary rams are similarly expensive tomanufacture, particularly withrespect to the guiding and sealing of the vanes which in addition areexposed at their peripheral edges to an unavoidable wear by dragging orsliding on the inner wall of the housing. Both cocking moment andbending moment act on the vanes, which make theconstruction of effectiveradial guides very difficult.

Axial piston motors and rotary rams or pumps are much more expensivethan gear motors or pumps. They are preferred primarily for the reasonthat they offer the advantage of shiftability and adjustability. Thisadvantage is thus obtained only in conjunction with a heavy additionalexpense.

The basic purpose of the invention is to produce apressure-medium-driven motor or a pump in which the above-discusseddisadvantages are avoided, and particularly a gear motor or a gear pumpwhich at low expense and favorable operating characteristics offers theadvantage of shiftability or controlability, which furthermore can beoperated easily and which at the same time permits higher rotationalspeeds, namely a hydrodynamic operation.

In a gear motor or a gear pump with more than two gears supported in ahousing which is provided with ports for feeding and discharging of apressure medium or a fluid to be conveyed, of which gears one gearthedriven gear if a pump or driving gear if a motor is connected to theoutput shaft or main shaft, the purpose of the invention is attained byproviding at least two additional gears which are connected solely tothe one gear and which are separated from one another by radiallypositioned housing sections. Such housing sections extends to the onegear and a port is provided therethrough on both sides of each of thegear meshing points. A pressure or suction chamber is also provided insaid housing section and said port in the adjacent radial housingsection opens thereto for feeding or discharging of a pressure medium ora fluid to be conveyed. Valves or the like are provided for theselective connection of the ports adjacent in or rather to a radialhousing section with one another or in a gear motor with the pressureline and the suction line of a pressure medium supply source or in agear pump a discharge point and one common or different supply point ofa fluid which must be conveyed or rather subjected to pressure. Thusthere is provided several connectedly arranged, common gear motor unitsbut having the advantageous feature that all these gear motor unitsconsist each of one individual and one common gear, that is, the drivenor driving 'gear and for each gear motor unit only one further gear. Theconstruction of the invention permits, by a suitable positioning of thevalves and at an unchanged pressure and volume of the pressure medium,the adjustment of selected ones, or all, of these gear motor units asdesired so that the gear motor at a constant product of torque androtational speed can be shifted or adjusted in a wide zone to a selectedvalue between low torque at high rotational speed and high torque at lowrotational speed. The

desired number of stages can be achieved in a simple manner by arranginga suitable number of further gears so that the steps, if necessary, canbe maintained very small. Due to the shiftability or adjustability ofthe gear motor a stepless adjustment provided at the pressure mediumsupply source is enlarged or through the latter (namely the steplessadjustments of the supply source) a stepless adjustment of the torque orthe rotational speed, is made possible, which stepless adjustmentexceeds the stepwise shiftability of the gear motor. Aside from theadvantage of a relatively low expense, which advantage is clear for gearmotors compared with other pressure-medium operated motors, the gearmotor of the invention aside from the advantage of its shiftability ishighly economical in that only for the first gear motor unit are twogears required and for each further gear motor unit only one furthergear is needed. The gear motors of the invention can for example be usedin machine tools, as for operating the main spindle on milling machines,whereby advantageously an adjustment with high torque and low rotationalspeed can be used for rough work, and without any loss in output anadjustment with low torque and high rotational speed can be used forfine work.

In one preferred embodiment of the invention, the driven or driving geardriven gear if a pump and driving gear if a motor is arranged centrallyand on its circumference the further gears are distributedcircumferentially equidistant from one another. By this arrangement, theradial forces are symmetrically distributed and asymmetrical stresses ofthe bearing of the driven or driving gear are avoided. This evendistribution of forces offers an additional advantage in the design andmanufacture of the gear motor or the gear pump of the invention.

A further feature of the invention consists in that the outer gears arein different tooth engaging positions. This is obtained by suitableselection of the central angle or the circumferential spacing of theouter gears as referred to the axis of the driven or driving gear and byselecting a suitable number of teeth and/or at equal circumferentialspacings a number of teeth of the driven or driving gear or the like,said number of teeth corresponding to a prime number, through whichparticularly at low rotational speeds a good synchronism of the gearmotor is achieved.

According to the invention, a particularly advantageous feature consistsin that the valves or the like are arranged within the radial housingsections, that in the outer zone of the housing two header channels areprovided which are positioned one behind the other in axial direction,each having a connecting branch or the like, that a connecting passageleads from each header channel to each valve, and that the adjustingmember of the valve is constructed like a rotary piston and is providedwith angularly offset valve ports. Said valve ports selectively connectthe two header channels to the two ports leading to the meshing pointsor they connect the two ports to one another with a simultaneousblocking of the connecting passages. Thus, the gear motor or the gearpump by internally containing the valves attains a compact arrangementwhich can be manufactured easily, the valves can be fitted easily andtwo related functions can be performed simultaneously by each valve. Inaddition to the advantages of economy, the operation of the valving ismade easier.

For use as a gear pump, a desireable feature of the invention consistsin that if the valves are arranged inside the housing, a header channelis arranged for the ports on the suction side in the outer zone of thehousing, from which header channel a connecting passage is lead to eachvalve, and that the ports on the pressure side extend separately fromone another beyond the valves each to one outlet port, with connectingbranches or the like. Through this construction it is possible topressurize, by means of a driving motor with the gear pump, severalsupply points separately from one another at different amounts and/orpressures.

Furthermore according to the invention in the pressure or suctionchambers in front or behind the meshing points there are insertedfluid-carrying wedges or the openings of the ports which openings facethe meshing points are divided approximately deltoid. The kinetic energywhich the pressure medium has at a great flow speed necessary forachieving high rotational speeds through this construction does not acton the meshing point, rather it is directed by the flowing pressuremedium to the teeth of the central gear and the respective outer gear,which teeth are to be driven.

A further feature of the invention is that the wall sections whichradially enclose the outer gears are recessed in comparison with saidgears, which reduces the pressure onto the bearings of the outer gearsand, particularly in case of hydrodynamic operation, reduces thefriction between the flowing pressure medium and these wall sections.

A still further feature of the invention is that it is possible for thevalves to be united in a single valve member with a common controlmember. It is further possible to use an operating member provided withone single control member, such as, in the case of valve members whichare constructed like rotary pistons with control positions positionedangularly to one another, providing torque-transmitting elements, aspinions, on each of the several adjusting members and, as a commonoperating member, a disk or a ring arranged concentrically to the axesof the adjusting members, which disk or ring corresponding with therequired control positions of the adjusting members is providedsegmentally with torque transmitting elements, like toothed sections.Together with economy of space and structural simplicity, this makes itpossible to shift the gear motor or the gear pump in a simple manner.

In this respect a particularly advantageous construction consists inthat according to the invention there is provided on the disk or thering as operating member for each adjusting member at least one singletooth as a torque-transmitting element, and on each adjusting memberthere is provided a small disk with at least one slot for the singletooth or several single teeth, and that a circular locking disk isprovided coaxially on the disk or the ring and curved surfaces adjustedto the radius of the locking disk are provided on the small disks insuch a manner that the small disks are rotated at a predetermined angleby means of one single tooth and the slot and are locked in theirrespective position by engagement of the locking disk into the curvedsurfaces, if necessary, with the support of one of the single teeth.

Finally it is suggested according to the invention that the housing becomposed of at least three platelike members of which the two outermembers contain the bearings for the shaft or axis of the central gearand the further gears and one of the header channels each,advantageously in form of an axially directed annular groove and alsothe connecting passages and that the central member or members have thewall sections which are positioned radially to the driven or drivinggear and the further gears, the radial housing sections with the portsand if desired the fluid-carrying wedges. In this construction the partsof the housing can be manufactured in an economical manner, preferablyby casting and can be accurately and easily worked by means of ordinarymachines and devices.

The character of the invention is illustrated in the drawings, in which:

FIG. 1 is a central, sectional view along the line II ofa gear motor,shown in FIG. 3.

FIG. 2 is a crosssectional view along the line IIII of FIG. 3 of thegear motor, shifted at 45 compared with the illustration of FIG. 1.

FIGS. 3-5 are cross-sectional views along the line III-III of FIGS. 1and 2 of the gear motor in three different positions.

FIG. 6 is an indicator diagram of this gear motor.

FIGS. 7a and 8a are enlarged fragments of a portion of the gear motor ofFIGS. 3-5 with different positions of the valve.

FIGS. 7b and 8b illustrate unwindings of these valves in their positionsaccording to FIGS. 7a and 8a.

FIGS. 9a to 12a schematically illustrate the gear motor in its differentpositions.

FIGS. 9b to 12b schematically illustrate an operating mechanism for thisgear motor in the positions corresponding to FIGS. 9a to 12a.

FIGS. 90 to 12c are diagrams of the performance figures of this gearmotor in the different positions.

FIG. 13 is a schematic and cross-sectional view of a gear pump takenalong a plane perpendicular to the axis.

The construction according to FIGS. 1-12 permit both a use as a gearmotor and use as a gear pump while the construction according to FIG. 13is for a gear pump.

According to the drawings, a gear motor or a gear pump comprises ahousing 1 or 1' (the primed numerals referring to FIG. 13) consisting ofthree platelike members 11, 12 and 13 or 11, 12' or 13 assembled bymeans of screw connections 14, a driven or driving gear 2, a gear, andfurther gears 3.

The central (whether driven or driving) gear 2 is, according to FIGS. 1and 2, rotatably fixedly connected to an output or main shaft 21 by akey 22 and is supported by means of needle bearings 23 which are securedwith snap rings 24,25 and a retaining ring 26 by means of screwconnections 27 in suitable openings of the platelike members 11 and 13or 11' and 13' in the housing 1. A seal ring 28 is arranged in theretaining ring 26.

The further (outer) gears 3 are, according to FIG. 2, supported onshafts 32 by means of needle bearings 31, which shafts are positioned incorresponding openings of the platelike members 1 1 and 13 or 11 and13'.

The outer gears 3 engage individually the central gear 2 at the severalmeshing points E and are separated by radially positioned housingsections 121 which extend to a point close to the central gear 2. Thecentral gear is thereby arranged centrally and the outer gears 3 arearranged along its circumference at equal pitch distances to oneanother. According to FIG. 7a the outer gears 3 are, by selecting anumber of teeth of the central gear 2 which number of teeth correspondsto a prime number, in constantly changing tooth engaging positions withrespect to one another.

Valves 5 are arranged in the radial housing sections 121 of theplatelike member 12 of the housing 1. These valves consist of a valvebore 51 which is axially parallel to the axis of the gear motor or thegear pump and a rotary-pistonlike adjusting member 52, the two controlpositions of which can be obtained by a rotation of 90.

Ports 61 and 62 for feeding and discharging of a pressure medium or afluid to be conveyed extend through the radial housing sections 121 fromthe valves 5 to the adjacent meshing points. Fluid-carrying wedges 122are inserted in the pressure or suction chambers in front and behind themeshing points E. In other words, the ports 61 and 62 are dividedapproximately deltoid at their openings toward the meshing points E.

In the outer zone of the housing 1, there are provided two headerchannels 63 and 64, each with one connecting passage 65 or 66, whichheader channels are positioned approximately in an axial direction onebehind the other. The header channels 63 and 64 are recessed in form ofaxial annular grooves in the plate-like members l1 and 13. Oneconnecting passage 67 or 68 extends from each header channel 63,64 toeach valve 5.

In the adjusting members 52 of the valves 5 there are arrangedconnecting passages 54 in such a manner that selectively andinterchangeably the ports 61 and 62 which are positioned adjacent oneanother in a radial housing section 121 by blocking the connectingpassages 67 and 68 can be connected to each other (FIG. 7a) or the port61 can be connected to the connecting passage 67 and the port 62 to theconnecting passage 68 (FIG. 8a). As is not further illustrated, in agear motor the header channel 63 is connected through its connectingpassage 65 to the pressure line and the header channel 64 is connectedthrough its connecting passage 66 to the suction or return line of apressure medium supply source. Of course, by reversing the feeddirection, the direction of rotation of the gear motor can be reversed.For a gear pump wherein the drive takes place from the main shaft 21, acorresponding operation is obtained, the only difference being that theheader channels 63 and 64 must be connected to the discharge point andto the supply point respectively of the fluid to be conveyed.

A common header channel 63" with connecting branch 65' is arrangedaccording to FIG. 13 in the gear pump (shown in a top view) in the outerzone of the housing 1 for the ports 61 on the suction side and theconnecting passages 67 The ports 62 on the pressure side are, however,separate from one another and extendoutwardly beyond the valves 5 eachwith one separate outlet passage 69 with connecting branches 69a. Thismakes it possible to supply from a storage reservoir or another fluidsource a number of different places with fluid, which number can be ashigh as the number of gear motor units or outlet passages 69. Dependingon the position of the valves, these places can be provided withdifferent selected pressures depending on the number of gear motor unitswhich act onto a particular outlet passage 69.

According to FIGS. 3-5 the wall sections 123 which radially enclose theouter gears 3 and which are positioned opposite the meshing points Eare, following the opening of the ports 63, arranged in stages, namelyrecessed opposite the gears 3 in their sections 124 so that a slightlylarger flow cross section exists and pressure and friction are reducedin this zone. As is not further illustrated, common open pockets towardthe pressure and suction side are provided at the meshing points E,through which pockets the pressure medium can flow from or enter intothe tooth chambers which narrow downin front of the meshing point andenlarge after the meshing point.

FIGS. 3-5 and FIGS. 7a and 8a indicate in dashdotted lines the positionof the connecting passages 68 which are positioned above the sectionalplane and of their common header channel 64.

FIG. 7a in connection with FIG. 7b and FIG. 8a in connection with FIG.8b illustrate the operation of a valve 5 whereby FIGS. 7b and 8billustrate in an overlap unwindings of the valve bore 51 and of theadjusting member 52 corresponding to the valve positions of FIGS. 7a and8a and also starting at the point A and going in clockwise direction.The angle marks 90, 180, 270 and 360 0 are thereby identified byvertical dash-dotted lines. The ports 61 and 62 and the connectingpassages 67 and 68, closer to their openings into the valve bore 51, areillustrated in full lines, the valve ports 53 and 54 in dashed lines.Point B of the adjusting member 52 is opposite point A in the positionaccording to FIGS. 7a and 717, from which it reaches the position ofFIGS. 8a and 8b by rotating the adjusting members 52in direction of thearrow C. In the position according to FIGS. 7a and 7b, the connectingpassages 67 and 68 and the valve ports 54 are blocked and the ports 61and 62 are connected by means of the valve port 53. After rotating theadjusting member in direction of the arrow C, the position according toFIGS. 8a and 8b is obtained so that the connecting port 67 is connectedto the port 61 through the valve port 63 and the port 62 is connected tothe connecting passage 68 through the valve port 54.

According to FIGS. 1, 2 and 9b to 12b, the valves are associated with anoperating member, which is provided with one single control member inform of a control lever 71, which operating member consists of a disk 72which is concentric to the valves 5 or the axes of the adjusting members52. This disk is equipped with torque transmitting elements forcooperation with torque transmitting elements secured on the adjustingmembers 52.

According to FIGS. 1 and 2, the disk 72 is rotatably supported in arecess of a platelike member of the housing 1, which member follows onthe outside the platelike member 11, and is connected rotatably fixed tothe control lever 71 by means of a screw connection 73. The plate likemember 15 is also provided with further recesses which are covered atthe outside by a lid 151 in the zone of the valves 5.

On the disk 72, there are arranged, as a part of the operating member oras torque transmitting element, single teeth 74, namely 74a, 74b and74c, and on each adjusting member 52, one small disk 75, namely 75a, 75band 750 with at least one slot 76 for one of the single teeth 74. On thedisk 72 there are furthermore provided coaxially a circular locking disk77 and on the small disks 75 curved surfaces 78 which are adjusted tothe radius of the locking disk 77 in such a manner that the small disks75 are rotated at a predetermined angle by means of one single tooth 74and a slot 76 and are locked in their respective position by engagementof the locking disk 77 into the curved surfaces 78, if necessary, withthe support of one of the single teeth 74. In order to permit a rotationof the small disks 75 in this construction, recesses 79 are provided inthe swivel zone of the sections surrounding the slots 76 in the lockingdisk 77. Finally a release 76a for the single tooth 74b in the lastcontrol position is arranged in the small disk 75c by which, if desired,the feed path can at the same time be limited. The individual controlpositions are identified by stationary marks I to IV and a pointer Dconnected to the disk 72.

This construction permits the arrangement of the single teeth 74 in sucha manner that by means of the control member of the control lever 71,the valves 5 can be operated through the slots 76 and the small disks 75in a desired and useful sequence and also according to the switchpositions I to IV.

FIGS. 9a to 12a symbolically illustrate major parts of the gear motor incorresponding positions, according to FIGS. and 3, according to FIGS.11a and 4 and also according to FIGS. 12 and 5.

In FIGS. 90 to 12c, the performance figures are illustrateddiagramatically individually corresponding to the positions of FIGS. 9aor 9b to 12a or 12b. In FIG. 6 they are illustrated together in form ofan indicator diagram, whereby in FIG. 6 the control positions areidentified with I to IV, correspondingly the torque with Md, to Md andfinally the rotational speed with n, to

In the control position I according to FIGS. 3 and 9a to 90, only onegear motor unit is provided with pressure medium so that according toFIG. 6 at a high rotational speed n, produces a small torque Md,.

In the control position II according to FIGS. 4 and 10a to 10c, two gearmotor units are supplied with pressure medium, through which, startingfrom switch position I, a smaller rotational speed n n,/2 and a highertorque Md 2Md, are obtained as this is also illustrated in FIG. 6.

In the control position III according to FIGS. 11a to 11c, a furtherreduced rotational speed n, n,/3 produces a further increased torque MD,3Md,.

Finally in the control position IV according to FIGS. 12a to 12c, allgear motor units are supplied with pressure medium so that alsoaccording to FIG. 6 a low rotational speed n n,/4 produces a high torqueMd As can be recognized from the illustrated exemplary embodiment, oneof the valves 5 does not require an angular adjustability so that thisvalve can be omitted or can be replaced by a solid insert havingsuitable parts.

When the gear motor is used as a gear pump, the same possibilitiesexist, in a reversal of the working direction, to adjust the feedpressure and volume to the respective conditions. Thus, as in the gearmotor, by using a suitable number of outer gears in addition to thecommon driving gear, the number and fineness of the steps can beselected.

- The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A fluid-actuated rotary motor or pump, comprising:

housing means;

a central externally toothed gear supported for rotation;

a plurality of externally toothed outer gears spaced circumferentiallyabout the periphery of said central gear and in meshing engagement withsaid central gear, the spacing between each of the outer gears defininggenerally an arcuate segment portion;

individually actuable valve means positioned in said arcuate segmentportions between each of said outer gears and adapted to be controlledbetween first and second positions;

first and second separate annular chamber means spaced radiallyoutwardly of said valve means one of said chamber means being adapted tocontain fluid under a relatively high pressure and the other of saidchamber means being adapted to contain fluid under a relatively lowpressure;

first radially extending passageway means in said arcuate segmentportions for permitting a fluid transfer between said first and secondannular chamber means through said valve means when said valve means isin said first position;

second radially extending passageway means in said arcuate segmentportions for permitting a fluid transfer between the location of each ofthe meshing engagements between said outer gears and said central gearsthrough said valve means when said valve means is in said firstposition, each of said valve means, when individually in said secondposition, permitting a fluid transfer between said first annular chambermeans and one of said meshing engagement locations in one of saidarcuate segment portions and between said second annular chamber meansand the next adjacent meshing engagement location in said one arcuatesegment portion.

2. A fluid actuated rotary motor or pump according to claim 1, whereinsaid housing means comprises a central plate housing said central gearand said plurality of outer gears and two side plates fastened toopposite sides of said central plate and housing rotary support meansfor said central gear and said outer gears, said first and secondannular chamber means being each located in one of said side platesradially external to said outer gears.

3. A fluid actuated rotary motor or pump according to claim 2, includingmanually operable means connected to each of said valve means forindividually operating said valve means one at a time.

4. A fluid actuated rotary motor or pump according to claim 3, whereinsaid manually operable means comprises a rotatable lever and connectionmeans to each of said valve means for individually controlling theposition of each of said valve means one at a time as a function of theposition of saidlever.

5. A fluid actuated rotary motor or pump according to claim 1, includingwedge means in said second passageway means adjacent said locations ofmeshing engagement for splitting the fluid flow into and out of saidpositions of meshing engagement.

,6. A fluid actuated rotary motor or pump according to claim 5, whereinsaid wedge means causes the fluid -to be directed onto the teeth of saidgears at a location spaced from said points of meshing engagement.

1. A fluid-actuated rotary motor or pump, comprising: housing means; acentral externally toothed gear supported for rotation; a plurality ofexternally toothed outer gears spaced circumferentially about theperiphery of said central gear and in meshing engagement with saidcentral gear, the spacing between each of the outer gears defininggenerally an arcuate segment portion; individually actuable valve meanspositioned in said arcuate segment portions between each of said outergears and adapted to be controlled between first and second positions;first and second separate annular chamber means spaced radiallyoutwardly of said valve means one of said chamber means being adapted tocontain fluid under a relatively high pressure and the other of saidchamber means being adapted to contain fluid under a relatively lowpressure; first radially extending passageway means in said arcuatesegment portions for permitting a fluid transfer between said first andsecond annular chamber means through said valve means when said valvemeans is in said first position; second radially extending passagewaymeans in said arcuate segment portions for permitting a fluid transferbetween the location of each of the meshing engagements between saidouter gears and said central gears through said valve means when saidvalve means is in said first position, each of said valve means, whenindividually in said second position, permitting a fluid transferbetween said first annular chamber means and one of said meshingengagement locations in one of said arcuate segment portions and betweensaid second annular chamber means and the next adjacent meshingengagement location in said one arcuate segment portion.
 2. A fluidactuated rotary motor or pump according to claim 1, wherein said housingmeans comprises a central plate housing said central gear and saidplurality of outer gears and two side plates fastened to opposite sidesof said central plate and housing rotary support means for said centralgear and said outer gears, said first and second annular chamber meansbeing each located in one of said side plates radially external to saidouter gears.
 3. A fluid actuated rotary motor or pump according to claim2, including manually operable means connected to each of said valvemeans for individually operating said valve means one at a time.
 4. Afluid actuated rotary motor or pump according to claim 3, wherein saidmanually operable means comprises a rotatable lever and connection meansto each of said valve means for individually controlling the position ofeach of said valve means one at a time as a function of the position ofsaid lever.
 5. A fluid actuated rotary motor or pump according to claim1, including wedge means in said second passageway means adjacent saidlocations of meshing engagement for splitting the fluid flow into andout of said positions of meshing engagement.
 6. A fluid actuated rotarymotor or pump according to claim 5, wherein said wedge means causes thefluid to be directed onto the teeth of said gears at a location spacedfrom said points of meshing engagement.